For general shell
script to execute SQL statements does not require the environment as those
required parameter might be set already for the sessions. But when it comes to Crontab
job, script will run independently from other sessions and it needs all the required
parameter to be set inside the script.

What are the
required parameters to run a SQL in a Crontab shell script?

1.Oracle SID

export ORACLE_SID=

2.Oracle
Base(optional) & Oracle Home

export ORACLE_BASE=

export ORACLE_HOME=

3.Set the Path for
sqlplus executable or directly call the sqlplus from ORACLE_HOME/bin directory.